1. Technical Field
The present invention relates to recording/reproducing methods for hard disk drives, and more particularly to techniques for recording and reproducing audio-visual data (hereinafter referred to as AV data).
2. Description of the Related Art
A typical storage medium to record AV data such as TV programs is magnetic tape, and video tape recorders (hereinafter referred to as VTRs) for recording AV data on this magnetic tape are widely used. VTRs are used not only for recording TV programs but also for reproducing video tape recorded movies and other programs (they are sometimes referred to as simply programs, including TV programs).
In the VTR described above, there are the following problems and demands. First, in the case where a plurality of programs have been recorded on a single video tape, fast forward or reverse winding of the tape for queueing-up of a program to be reproduced is time-consuming. This is because magnetic tape is a storage medium unsuitable for random access. Also, for example, there is a demand that while recording a TV program, viewers desire to view the recorded program from an arbitrary point, or that while recording a certain TV program, viewers desire to view another program previously recorded. Although this demand suggests the appearance of video recorders having a simultaneous recording/reproducing function, conventional VTRs are not equipped with such a function. With respect to the above problem, employing a hard disk drive, which is excellent in random access, in recording and reproducing AV data has been proposed and in some cases has been put to practical use.
AT attachment interfaces standardized by ATA standards have been designed with the primary object of handling data for computers. For this computer data, data perfection is the most important element and devices are required to maintain data as perfectly as possible.
On the other hand, application data for AV (AV data) is not required to be as perfect as computer data, but has a characteristic that a certain amount of data must be handled continuously within a predetermined time. That is, AV application data systems have no great problem even if each individual data includes an imperfect portion, but has a problem if a video stops, such that continuity in data is lost. Since AV application data is usually a group (or lump) of data arrayed continuously on a time axis, it is called a stream. Therefore, in this specification, such a data group is likewise called a stream and data included in the stream is called stream data.
In the case where AV data having such characteristics are recorded and reproduced by employing conventional hard disk drives, the conventional hard disk drives cannot satisfy a user""s operability requirements because such drives have been designed for reading out or writing data suitable for computers.
Accordingly, it is an object of the present invention to provide a data recording/reproducing unit, a data recording/reproducing method, and a hard disk controller suitable for recording/reproducing AV data on or from a hard disk or other storage media that can be accessed randomly.
The present invention is characterized in that it enhances user friendliness in handing AV data, by defining regions, on which a stream, i.e., a lump of data continuous in a time-series manner is recorded, on a hard disk and accessing that data lump in the unit of the recording region. That is, the data recording/reproducing unit of the present invention comprises: a randomly accessible hard disk on which a lump of data continuous in a time-series manner is recorded; recording-region setting means for defining a plurality of recording regions for the data lump with respect to the hard disk and allocating sectors to each of the recording regions, the sectors being given consecutive numbers; and a controller for controlling recording/reproduction of the data lump with respect to the hard disk by specifying the recording region and the sectors.
Accordingly, the data recording/reproducing unit of the present invention, recording or reproduction of data, for example, TV programs, can be executed, by specifying the aforementioned recording regions and sectors. Also, in the data recording/reproducing unit of the present invention, a plurality of recording areas are defined. For example, in the case of two recording regions, the process of recording a video on one recording region and the process of reproducing another video from another recording region can be performed in parallel.
In the data recording/reproducing unit of the present invention, the recording/reproduction of data is performed in the order of the numbers of the sectors, given the consecutive numbers. More specifically, when recording data, the data is written in the order of the sector having a smaller number, and in reproducing data, the data is read out in the order of the sector having a smaller number.
Here, in conventional hard disks, the sectors are given logical consecutive numbers beginning with zero, i.e., logical block addresses (LBAs), respectively. However, the recording regions and sectors of the present invention are provided separately from conventional LBAs. Note that in the present invention, the consecutive numbers given to the sectors are called stream LBAs.
In accordance with the present invention, there is provided a data recording method comprising the steps of: developing a data stream on a data storage medium accessible in random, the data stream being a unit in which a group of data continuous along a time axis is recorded; allocating to the data stream a plurality of sectors given consecutive numbers; and specifying the number of the sector at which writing of the data is started, and then writing the data to the sectors in the order of the consecutive numbers. In this data recording method, a single stream may be developed on the storage medium, however, there is a need to develop a plurality of data streams in order to execute simultaneous recording-reproduction described previously. In addition, if a plurality of data streams are present, different groups of data can be recorded in the same time period on one data stream and another data stream of the plurality of data streams, respectively. In recording/reproducing AV data, there is a need to transfer 1.5 M bytes of data for each 0.5 seconds. If we assume the data transfer capability of the interface of a hard disk drive is 3 M byte/s, it becomes possible to record different groups of data in the same time period, by alternately performing the process of writing one group of data to one data stream at a rate of 1.5 M bytes/sec and the process of writing the other group of data to another data stream at a rate of 1.5 M bytes/sec.
In accordance with the present invention, there is provided a data recording method comprising the steps of: developing a plurality of data streams accessible at random, the data streams being units in which a group of data continuous along a time axis is recorded; giving a number to each of the plurality of data streams developed on the data storage medium on a data storage medium; allocating to each data stream a plurality of sectors given consecutive numbers; and writing the data group to the sectors in the order of the consecutive numbers, and if another group of data is present continuously after the writing of the data group reaches the sector of the last number of the consecutive numbers, writing the other data group in sequence from its sector given the first number of the consecutive numbers. In the case where recording is performed up to the last data stream LBA when AV stream data is not completed, i.e., when a TV program is being recorded, this data recording method records the TV program continuously from the first data stream LBA. In this specification, this recording is called seamless recording.
In accordance with the present invention, there is also provided, in a method of reading out data from a storage medium on which a plurality of data streams have been recorded in data stream units, each data stream being a group of data continuous along a time axis, a data reproducing method, comprising the steps of: specifying a data stream on which data to be reproduced has been recorded; specifying a start position in the specified data stream at which the data is read out; and starting reading of the data from the specified position. In this data reproducing method, the data stream is divided into micro-units having a predetermined capacity, and each micro-unit is given consecutive numbers. Specification of the start position at which the data is reproduced can be performed by specifying the number. The number given to the micro-unit refers to the data stream LBA.
In accordance with the present invention, there is also provided a method of reading out data from a storage medium on which a plurality of data streams have been recorded in data stream units, each data stream being a group of data continuous along a time axis, the method comprising the steps of: specifying a data stream on which data to be reproduced has been recorded; specifying a start position in the specified data stream at which the data is read out; and starting reading of the data from the specified position, and after the reading of the data has reached the end point of the data stream, reading out data in sequence from the start point of the data stream. In the case where reproduction is performed up to the last data stream LBA during reproduction of a recorded TV program, this data reproducing method performs reproduction continuously from the first data stream LBA. In this specification, this reproduction is called seamless reproduction.
While recording of data and reproduction of data have been described separately, the present invention includes the process of recording data and the process of reproducing data in parallel. That is, in accordance with the present invention, there is provided a data recording/reproducing method comprising: a writing process having (a) a step of developing a plurality of data streams on a data storage medium accessible in random, the data streams being units in which a group of data continuous along a time axis is recorded, (b) a step of allocating to each data stream a plurality of sectors given consecutive numbers, and (c) a step of writing data to the sectors in the order of the consecutive numbers; and a reading process having (a) a step of specifying the data stream on which data to be reproduced has been recorded, (b) a step of specifying a start position in the specified data stream at which data is read out, and (c) a step of starting reading of data from the specified position; wherein the writing process and the reading process are executed in parallel.
The present invention is also executed as the data recording-reproducing method, as described above. However, the invention may be carried out as a controller for hard disk drives. Therefore, in accordance with the present invention, there is provided a hard disk controller for controlling reading and writing of data with respect to a hard disk drive, the hard disk controller comprising: recording-region setting means for defining a plurality of recording regions, on which a lump of data is recorded, with respect to a hard disk and allocating to each recording region a plurality of sectors given consecutive numbers; and data specification means for specifying data which is to be read out from or written to the hard disk, by specifying the recording region and the sectors.
Furthermore, the present invention may also be executed as a method of recording/reproducing a group of audio-visual data. Therefore, there is provided a method comprising the steps of: developing a plurality of data streams on a data storage medium accessible in random, the data streams being units in which the audio-visual data group is recorded; dividing each of a plurality recording regions into predetermined recording units; and performing recording/reproduction of the audio-visual data group for each recording region.